The growth and physiologic interactions of two oral bacteria, Fusobacterium nucleatum and Streptococcus sanguis, are being investigated. The two organisms from a coaggregating pair with a characteristic morphology known as a "corn cob". A medium has been determined which should allow the growth of the Streptococcus on limiting glucose and the Fusobacterium on a limiting amino acid. A means for the continuous sampling of the culture during bacterial growth has been established. The fluorometric determination of DNA has been evaluated for a measure of growth. Initial experiments to determine the sequence of use of glucose and amino acids for energy by F. nucleatum have begun. Samples of the growth medium from F. nucleatum have been provided for assay of the characteristic effects of butyric acid in a tissue culture system.